Non-resonant electromagnetic energy sensor

ABSTRACT

A non-resonant electromagnetic energy sensor includes an electromagnetic energy source and an electromagnetic energy detector in communication with the interior volume of a measuring region through which an analyte passes. The electromagnetic energy detector detects the signal variations of the electromagnetic energy within the measuring region caused by the perturbation of the electromagnetic energy field due to the passage of the analyte therethrough and responds to these signal variations by generating output signals. These output signals may then be received by electronic circuitry designed for quantitative and/or qualitative detection of the flow of various substances including individual particles, particles flowing as a continuum, and non-turbulent fluids.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent application,Ser. No. 09/421,670 filed Oct. 20, 1999 now U.S. Pat. No. 6,208,255.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to sensors utilizing electromagneticenergy for detecting the passage of substances through a chamber, andmore particularly to such sensors in which said electromagnetic energyis non-resonant.

2. Description of the Related Art

Sensors which use electromagnetic energy for detecting the passage of asubstance through a chamber are well known in the art and have foundapplications in a number of industries. For example, in the agriculturalindustry, electromagnetic sensors have been used for monitoring seedplanting operations as disclosed in U.S. Pat. No. 4,246,469 to Merlo,and for monitoring crop moisture as disclosed in U.S. Pat. No. 5,708,366to Nelson. In the petroleum industry, sensors using electromagneticenergy have been used for determining solid-to-liquid ratios in aflowing petroleum stream as disclosed in U.S. Pat. No. 5,644,244 toMarrelli et al.

Unfortunately, the inventions disclosed in these patents fail to solvethe need of providing a single sensor that can be used for detecting thepresence, flow-rate, and/or volume of various substances, whether thesubstance being measured is a solid, a liquid, or a gaseous materialsuch that only one sensor is needed for all the monitoring needs of auser. Nor do these sensors provide for both quantitative and qualitativedetection of substances. Thus, those concerned with these and otherdeficiencies recognize the need for an improved electromagnetic energysensor.

BRIEF SUMMARY OF THE INVENTION

A non-resonant electromagnetic energy sensor which generates outputsignals upon the quantitative and/or qualitative detection of the flowof various analyte substances including solid particles flowing asdiscrete individual particles or as a continuum, as well as the flow ofliquids and/or gaseous analyte substances. The non-resonantelectromagnetic energy sensor may be electronically interfaced withvarious types of electronic circuitry whereby the generated outputsignals may be used for monitoring a variety of flowing substances, forexample, seed flow in an agricultural planter, crop yield on a combineharvester, and flow rates of liquids or gaseous fluids under pressure.

The sensor comprises a housing having wall members defining a chamberhaving an interior volume. The sensor is designed to be interposed alonga length of conduit through which the analyte will pass. Anelectromagnetic energy source and an electromagnetic energy detector arein communication with the interior volume of the chamber. Theelectromagnetic energy source propagates non-resonant electromagneticenergy of a predetermined frequency and amplitude into a measuringregion within the interior volume of the chamber. The electromagneticenergy detector detects the signal variations of the electromagneticenergy within the measuring region caused by the perturbation of theelectromagnetic energy field due to the passage of the analytetherethrough and responds to these signal variations by generatingoutput signals. By interfacing various types of electronic circuitry toreceive these output signals, the non-resonant electromagnetic energysensor may be used to quantitatively and/or qualitatively detect theanalyte, whether the analyte is a solid flowing as discrete particles oras a continuum, or whether the analyte is a flowing liquid, or flowinggaseous substance.

Other objects, advantages, and novel features of the present inventionwill become apparent from the following detailed description of theinvention when considered in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a cross-sectional view of one embodiment of the non-resonantelectromagnetic energy sensor of the present invention interposed alonga length of conduit;

FIG. 2 is a schematic diagram of the preferred electronic circuitry forthe non-resonant electromagnetic energy sensor;

FIG. 3 is a side elevation view of a planter showing one application foruse of the non-resonant electromagnetic energy sensor of the presentinvention;

FIG. 4 is a cross-sectional view showing two non-resonantelectromagnetic energy sensors of the embodiment of FIG. 1 interposedalong a length of conduit;

FIG. 5 shows sample output signals from the non-resonant electromagneticenergy sensors from the application of FIG. 4;

FIG. 6 shows the output signals of FIG. 5 differentiated with respect totime;

FIG. 7 is a cross-sectional view showing two non-resonantelectromagnetic energy sensors of the embodiment of FIG. 1 interposedalong a length of conduit in which solid analyte particles are flowingtherethrough as a continuum;

FIG. 8 shows sample output signals from the non-resonant electromagneticenergy sensors from the application of FIG. 7;

FIG. 9 shows the output signals of FIG. 8 after application of samplingand correlation techniques;

FIG. 10 is a cross-sectional view showing two non-resonantelectromagnetic energy sensors of the embodiment of FIG. 1 interposedalong a length of conduit in which a liquid or gaseous analyte fluid isflowing therethrough; and

FIG. 11 is a cross-sectional view of another embodiment of thenon-resonant electromagnetic energy sensor of the present inventioninterposed along a length of conduit which utilizes Doppler techniques;

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings, wherein like reference numerals designateidentical or corresponding parts throughout the several views, FIG. 1shows a cross-sectional view of one embodiment of the non-resonantelectromagnetic energy sensor (10) of the present invention. In the FIG.1 embodiment, the sensor (10) comprises a housing (12) having wallmembers (13) defining a chamber (16) having an interior volume (18). Thesensor (10) is designed to be interposed along a length of conduit (19)through which the material or substance to be analyzed (hereinafterreferred to as the analyte (14)) will pass. The direction of travel ofthe analyte (14) is represented by the arrow (15). At least a portion ofthe interior volume (18) of the chamber (16) is disposed along the pathof travel of the analyte (14) passing through the conduit (19). Anelectromagnetic energy source (20), and an electromagnetic energydetector (22) are in communication with the interior volume (18) of thechamber (16) through input and output ports (24, 26), respectively,disposed in the wall members (13) of the chamber (16). As will bediscussed in further detail later, the electromagnetic energy source(20) propagates electromagnetic energy (30) of a predetermined frequencyand amplitude into the interior volume (18) of the chamber (16) throughthe input port (24). The electromagnetic energy detector (22), incommunication with the interior volume (18) of the chamber (16) throughthe output port (26), responds to signal variations of theelectromagnetic energy (30) therein caused by the perturbation of theelectromagnetic energy field due to the passage of the analyte (14)therethrough.

It should be understood that all materials have material parametervalues as determined by the material's permittivity, permeability, andconductivity properties. These relate to the material's dielectric,magnetic and conductive properties respectively.

Thus, as the analyte (14), passes through an electromagnetic energyfield (30), the electromagnetic energy signal will perturb (i.e. vary).It is this variation in the electromagnetic energy signal, which thepresent invention detects and utilizes by generating output signals foruse in various applications as will be discussed in detail later.

In one preferred embodiment, a portion of the chamber (16) preferablyincludes a measuring region (32) disposed between an evanescent upperregion (34) and an evanescent lower region (36) of the chamber (16). Thewall members (33) of the measuring region (32) are comprised of adielectric material such as polymer, ceramic, or any other suitabledielectric material. The dielectric material makes the measuring region(32) of the chamber (16) significantly “electromagnetically larger” incross-section than the evanescent upper and lower regions (34, 36) ofthe chamber (16). Thus, as illustrated in FIG. 1, the above region (34)and the below region (36) act as waveguides which “cut-off” theelectromagnetic energy (30) and confine it within the measuring region(32), such that the amount of electromagnetic energy (30) that canpropagate out of the measuring region (32) is limited. The measuringregion (32) thereby defines a region within the chamber (16)substantially filled with electromagnetic energy (30). It should beunderstood that “waveguide” as used in this specification, means anystructure that guides electromagnetic energy regardless of wavelength.

It should also be understood that in some applications, it may bepossible to eliminate the wall members (33) of the measuring region(32). With no walls members (33) the resultant measuring region (32)will be physically and electromagnetically larger than evanescentregions (34) and (36). Those skilled in the art will also appreciatethat the evanescent regions (34) and (36) could be replaced with filterstructures and other band stop structures to prevent or control theamount of electromagnetic energy exiting along the length of the chamber(16).

The frequency and amplitude of the electromagnetic energy (30)propagated into he measuring region (32) may vary from application toapplication and depends on such factors as the size of the analyte (14)to be detected, which may dictate the desired internal diameter of themeasuring region (32). Other factors which may effect the frequency andamplitude of the electromagnetic energy (30) might include the expectedvelocities of the analytes flowing through the chamber, the number ofanalytes expected to pass through the chamber per unit of time, andavailable space due to design considerations of the equipment on whichthe material sensor (10) is placed. For example, if the conduit (19) iscircular in cross-section, the internal diameter of the measuring region(32) is dictated by the following equation:$D < \frac{1.8412\quad v}{\pi \quad f\sqrt{ɛ_{r}}\sqrt{u_{r}}}$

D=internal diameter of the measuring region (32) (inches)

v=velocity of light (inches/sec)

f=frequency of the electromagnetic energy source (20) (Hz)

ε_(r)=effective dielectric constant of the analyte (14) and measuringregion (32)

u_(r)=effective relative permeability of the analyte (14) and measuringregion (32)

For example, assuming the frequency of the electromagnetic energy (30)from the electromagnetic energy source (20) is 10 GHz, and that theanalyte (14) is dry sand having an assumed dielectric constant of 4, theinternal diameter of the measuring region (32) would have to be lessthan 0.345 inches. At the same frequency (i.e. 10 GHz), if the analyte(14) is water having a dielectric constant of 80, the resulting internaldiameter of the measuring region (32) would have to be less than 0.23inches. Naturally, different electromagnetic energy source frequenciescould be used for different applications, with lower frequencies beingused if the internal diameter of the measuring region (32) needs to belarger for a particular application.

If interference to radio sets from any small leakage of electromagneticenergy (30) from the chamber (16) is of concern in a particularapplication of the material sensor (10) of the present invention, thoseskilled in the art will recognize that slight modifications of thematerial sensor (10) can be made to move the operating frequency of theelectromagnetic energy (30) to one of the ISM bands to limit suchinterference. Additionally, if multiple sensors (10) of the presentinvention are to be used in close proximity in a particular application,those skilled in the art will recognized that various modulation formatscould be used with the electromagnetic energy source (20) to enhance thesignal-to-noise ratio to reduce mutual interference from adjacentsensors (10).

It should be appreciated that although the preferred embodimentdiscloses the use of a separate electromagnetic energy source (24) anddetector (26), it is possible that a single component such as a Gunndiode, acting as both the energy source and detector, may be used in thepresent invention. Accordingly, if such a device is used, only one portthrough the wall members (13) of the chamber (16) would be necessary.This single port would then act as both the input port (24) and theoutput port (26).

FIG. 2 is a schematic diagram of the preferred electrical circuit (40)for the material sensor (10) of the present invention. The mainelectrical components of the electrical circuit (40) preferably includesa power source (42), a power regulator (44), an electromagnetic energysource (20) (such as an oscillator (46)), an electromagnetic energydetector (22) (such as a mixer (48)), a buffer amplifier (50), and asignal processor (52).

The power source (42) is preferably a 12 volt DC battery. Together, thepower source (42) and the power regulator (44) provide constant power tothe circuit (40). The preferred oscillator (46) for generating theelectromagnetic energy (30) for propagation into the measuring region(32) of the chamber (16) is a Mini-Circuits POS 1025 operating in the800 MHZ range and having a power output of 9 dBm. The preferred mixer(48) for detecting the electromagnetic energy signal variations is aMini-Circuits ASK-2-KK81. It should be understood that theelectromagnetic energy (30) generated by the source (20) is comprised ofboth electrical and magnetic components having non-equal total peakvalues. Thus, the electrical circuit (40) is referred to as“non-resonant” electromagnetic energy circuit.

It should also be understood that, while the preferred embodimentutilizes a 12 volt DC battery power source and a voltage regulator toprovide a constant power source to the circuit and to minimize theamount of noise on the power line fed to the electromagnetic energysource and the rest of the circuit, any other type of voltage sourcesmay also be used, such as solar cells, generators, etc. In addition,rather than a voltage source, the power source may be any type of acurrent source for compatible electromagnetic energy sources. Further,depending on the power source, a power regulator may or may not benecessary, so long as the power source is capable of providing aconstant and relatively noise-free power source to the circuit. Forexample, these other power sources might have their noise levelcontrolled with amplitude, phase, or frequency control loops without theneed for separate power regulators.

Before discussing the operation of the sensor (10) of the presentinvention, a brief discussion of electromagnetic energy and resonancecircuits is helpful to the understanding of the present invention:

Resonance circuits can be characterized by considering what happens toenergy in a volume under consideration. For the purposes of this briefdiscussion, the volume under consideration is comprised of a firstvolume which exists between a reactanceless source sending energy intothe volume under consideration, and a reactanceless detector receivingenergy from the volume under consideration (the reactance of the sourceand of the detector is considered part of the volume underconsideration). The volume under consideration is also comprised of asecond volume which includes those volumes connected electromagneticallyto the first volume in a manner such that a change in the energy levelsof the second volume substantially effects the response existing betweenthe source and detector in the first volume.

It is understood that an electromagnetic source can absorb energy aswell as send energy. This action is often described in terms ofscattering parameters. For purposes of this brief discussion, we willconsider the net amount of energy delivered from the source as theamount sent minus the amount absorbed. A detector of the energy willabsorb some energy from the volume. This amount of energy absorbed bythe detector can be considered as part of the energy lost in the volume.The resistance associated with the source can also be considered to bepart of the energy absorbed or lost in the volume.

This analysis is in the frequency domain. A single frequency is used todiscuss a response. If the characteristics of the volume, the source,and the detector are linear, it is well known that analysis fordifferent types of signals can be obtained by superposition. One type ofsuperposition is that obtained from Fourier transformation.

The energy in the volume consists of magnetic and electric energy. Ifthere were no other losses, all the energy generated by the source inthe steady state would be dissipated by the losses associated with thevolume. (Keep in mind that the losses associated with the detector havebeen incorporated into the volume.) In the steady state, for acontinuous wave (cw) signal, the magnetic energy and the electric energyin the volume change with time in a sinusoidal manner. The total amountof electric energy in the volume at any one instance of time is equal tothe volume integral of the electric field energy at that time. Thecharacteristics of the medium in the volume is described by thepermittivity ∈=∈′−j∈″, the permeability μ=μ′−ju″, and the conductivityσ. The time average of the electric field energy is:

{overscore (W)}e=½∫∫∫ε′|E|²dV

where the integral is taken over the whole volume. This integral is formedia for which D=∈E. Since E varies with time sinusoidially (we assumeda sinusoidal variation with time), the energy varies from zero to a peakvalue twice during one cycle of the sinusoid.

Likewise, the time average magnetic field energy in the volume is:

{overscore (W)}m=½∫∫∫μ′|H|²dV

and again the integral is taken over the whole volume. This integralalso varies from zero to a peak value twice during one cycle. When thevolume is at resonance, the peak values of energy are equal. The timeaverage power dissipated in the medium is:

 {overscore (P)}_(d)=∫∫∫((σ+ωε″)|E|²+ωμ″|H|²)dV

When the time average of the electric field energy is the same as thetime average of the magnetic field energy, the volume is said to be inresonance. The source supplies the average power dissipated and thereactive energy is cycled back and forth between the magnetic andelectric energy. Since the total energy must be conserved, at resonance,when the electric energy is at its peak, the magnetic energy will bezero and vice versa. Note that at resonance, since the time average ofthe field energies are the same, the peak values are also the same—theyjust peak at different times.

The concept of equality of magnetic field energy and electric fieldenergy at resonance will be demonstrated by considering a series RLCcircuit. Assume that the voltage across the capacitor is V_(c)=Acos(ωt). The current through the series circuit is then I_(c)=→C_(a)ωAsin(ωt). The electric field energy is equal to ½CV². The magnetic

field energy is equal to ½LI². Since cosine peaks ninety degrees out ofphase with sine, the capacitive energy peaks when the inductive energyis zero and vice versa. Since the energies are related to voltage orcurrent squared, there are two peaks of energy per cycle.

For example, when the voltage across the capacitor is maximum at A, theenergy is related to A times A or A². When the capacitor voltage isconsidered one hundred eighty degrees later, the voltage is −A. Theenergy is related to −A times −A or again A². Completing the analysis,the capacitive energy is:

½CV²=CA² cos² (ωt)

and the inductive energy is:

 ½LI²=½C(LCω²)A² sin²(ωt)

The resonance condition for the series RLC circuit is w²LC=1. Atresonance the inductive energy is:

½LI²=½CA² sin²(wt)

This has the same magnitude as the capacitive energy. Similarrelationships hold for field energies integrated over the volume. Whenthe series RLC is not resonant, i.e. ω²LC is not equal to one, the peaksof magnetic and electric (inductive and capacitive) energy are still inthe same time relationship but their peak values are different.

Operation of the Non-Resonant Electromagnetic Energy Sensor

In operation, as explained briefly above, when the resonant frequency ofthe electromagnetic energy (30) is above the measuring frequency, andwhen the analyte (14) passes through the measuring region (32) of thechamber (16), if the analyte (14) is a dielectric analyte material, thedielectric analyte material (14) will perturb the electromagnetic energy(30) within the measuring region (32) by increasing the electric fieldenergy such that the total peak value of the electric field energycomponent approaches the total peak value of the magnetic field energycomponent, thereby causing the electromagnetic energy (30) to movecloser to resonance. Likewise, if the analyte (14) is a magnetic analytematerial, the magnetic analyte material (14) will perturb theelectromagnetic energy (30) within the measuring region (32) therebyincreasing the magnetic field energy such that the total peak value ofthe magnetic field energy component approaches the total peak value ofthe electric field energy component, thereby causing the electromagneticenergy (30) to move closer to resonance. As the electromagnetic energy(30) within the measuring region (32) moves closer to resonance, alarger signal variation is detected by the mixer (48) than is normallydetected when the electromagnetic energy (30) is farther from resonanceor at resonance. When the mixer (48) detects this increase in signalvariation, it produces a dc output signal which is then amplified andprocessed by the buffer amplifier (50) and signal processor (52)respectively.

By interfacing this output signal from the mixer (48) to a monitor orother various types of electronic circuitry, such as by electrical,magnetic or photoelectric coupling, the material sensor (10) may be usedfor detecting not only the presence or passage of solid, liquid and/orgaseous materials through the conduit (19), but also for quantitativeand/or qualitative determinations of those materials or substances. Forthe purpose of defining specific embodiments, examples of suchapplications are discussed in detail below.

Specific Embodiments of Possible Applications of the Material Sensor

1. Flow or No-Flow Monitoring

The above described material sensor (10) may be used, for example, on aconventional multi-row planter for detecting the flow, or interruptionthereof, of seed, fertilizer, insecticide, herbicide, etc., through theconduits of the planter.

Referring to FIG. 3, a conventional multi-row planter (60) is shown. Itshould be understood that the following discussion of the componentscomprising a conventional multi-row planter and its operation may varyamong the different makes and models of such planters, but all suchplanters are substantially similar in their structural components andoperation. The planter (60) includes a plurality of seed hoppers (62),one for each row, to hold and dispense the seed as the planter (60)traverses the field. Each row also typically includes one or two otherhoppers (63) for dispensing fertilizers, herbicides and/or insecticidesalong with the seed. For clarity and ease of discussion, however, thefollowing description will focus only the structure for dispensing seed.A conduit (19) attached to and disposed below each hopper (62) defines apath for the seed to travel through to the soil (66) to be planted.Disposed at the base of the hopper (62) or at the interface of thehopper (62) and conduit (19) is a metering device (67) which ideallypasses the seed, one at a time, into the conduit (19). The meteringdevice (67) is typically comprised of a rotating metering wheelinterconnected through chain drives (not shown) with the press wheel(68) of the planter (60) such that rotation of the press wheel (68)causes rotation of the metering wheel to dispense the seeds. Other typesof metering devices (67) may utilize positive and negative air pressuresto dispense the seed into the conduit (19) depending on the make andmodel of the planter.

Referring back to the cross-sectional view of FIG. 1, which is, forexample taken, along lines 1—1 of FIG. 3, the material sensor (10) isshown interposed in the conduit (19) along the path of travel of theanalyte (14) (i.e. the seed). The internal diameter of the measuringregion (32) of the chamber (16) of the sensor (10) is preferably thesame diameter as the conduit (19) above and below the measuring region(32) such that the seed (14) can pass through the measuring region (32)without obstruction. As discussed previously, the electromagnetic energysource (20) and the electromagnetic energy detector (22) are incommunication with one another through their respective input and outputports (24, 26). As the seed (14) passes through the elecromagneticenergy field (30) within the measuring region (32), the electromagneticenergy (30) is perturbed by the presence of the seed (14), causing themagnetic and electric field energy peak values to be brought closer toresonance (i.e. approach equality as previously discussed). The detector(22) (FIG. 2) detects this increase in signal variation and produces anelectrical signal output response as discussed above which can beutilized by various types of planter consoles or monitors (70) (FIG. 3)currently available and in common use by farmers with their planters.

By electrically, magnetically or photoelectrically coupling the signaloutput of the material sensor (10) with the electronic circuitry of aplanter console or monitor (70), visual and audible indication of theseed flow, or lack thereof, through each conduit (19) of the planter(60) may be performed. Such a console (70) is typically mounted withinthe cab of the tractor (not shown) pulling the planter (60). One type ofsuch a commercially available console or monitor (70) is a DJ 2100 asmanufactured by Dickey-John™. The console (70) preferably comprises aplurality of indicator lamps (72) corresponding to each row of theplanter (60). The indicator lamps (72) or other indicator means areresponsive to the electrical output signals generated by the materialsensor (10) to cause the lamps (72) to flash each time a seed passesthrough the measuring region (32) of sensor (10) interposed in theconduit (19). The operator will thereby have visual indication of thepassage of seed through all of the conduits (19) whose associated rowsare being planted. In addition to the indicator lamps (72), the console(70) may also include an alarm (74) which sounds when the sensors (10)do not detect seed flow within a predetermined time interval. Thus, ifthe operator fails to notice that a particular indicator lamp (72) isnot flashing, and therefore no seed is being planted in that row, anaudible alarm will warn the operator that a particular row is not beingplanted—which may be the result of an empty seed hopper (62), anobstruction blocking seed flow through the conduit (19), or possibly afaulty seed metering device.

In addition to merely detecting the flow of seed, or lack thereof,farmers also prefer to know the seed population, typically designated inseeds per acre. One way of obtaining seed population, is to determinethe amount of seed planted per unit of distance traveled by the planter(60). Thus, if the electronic circuitry of the console (70) is alreadyrecording the total number of seeds being planted as described above, asimple calculation familiar to those skilled in the art will readilyobtain seed population if the speed and/or distance traveled by theplanter (60) is also being monitored. Most monitors or consoles (70)available on the market will track the speed and/or distance traveled bythe planter (60) and therefore seed population can be readily obtained.Consoles (70) with associated circuitry able to calculate and displayseed population are disclosed in references such as U.S. Pat. Nos.4,137,529; 4,268,825; 4,333,096; and 4,710,757, the specifications ofwhich are incorporated herein by reference.

2. Particle Counting

In addition to merely detecting the presence of an analyte (14) passingthrough the measuring region (32), the sensor (10) of the presentinvention may also perform qualitative and quantitative analysis on theanalyte (14) during passage through the measuring region (32).

A practical use of such qualitative and quantitative analysis of ananalyte (14) can again be found in the example of the seed planter (60)of FIG. 3. It should be appreciated that the accuracy of the seedmonitors (70) as described above is dependent upon the ability of thematerial sensor (10) to distinguish between dirt, dust, chaff and seedfragments, and those whole seeds which will germinate into a plant.Additionally, during high rates of seed flow or when variation in seedsizes cause two or more seeds to drop at the same time (doubles), thematerial sensor (10) must be able to distinguish the seeds so thatdoubles are not counted as one. Further, the material sensor (10) mustalso be sensitive to moisture in order to distinguish “good” seed from“bad” seed so that only “good” seed is counted.

Thus, in order to accomplish these tasks, and thereby obtain greateraccuracy than currently available seed counters, the material sensor(10) of the present invention has the ability to measure the dielectricmass of the analyte (14) passing through the measuring region (32) andthereby only counts those analytes (14) falling within a specified rangeof acceptable dielectric mass.

As explained above, all materials or substances have a specificdielectric constant. Additionally, all similar materials having asubstantially similar density, volume and moisture content, and thus adielectric mass, will fall within a defined range of dielectricconstants (as is the case with a particular variety and type of cropseed purchased from a seed dealer). Accordingly, when planting aparticular type and variety of seed, each “good” seed (14) passingthrough the measuring region (32) of the material sensor (10), willperturb the electromagnetic energy (30) within the measuring region (32)a certain expected amount within a quantifiable range. By providingelectronic circuitry to “program” the detector (22) of the materialsensor (10), to detect only those signal variations falling within an“acceptable” range, the material sensor (10) can be set to only detect“good” seed. If the signal variation of a passing analyte (14) does notfall within this predetermined range of acceptable signal variations,that analyte will not be counted by the monitor (70). In this way, dirt,chaff, seed fragments, or seeds not having at least a particular volumeand mass, and thus not likely to germinate, will not be counted. Thus,the material sensor (10) of the present invention may provide a moreaccurate and reliable means for determining seed plant population atplanting than previous types of electromagnetic material sensors, suchas that disclosed in U.S. Pat. No. 4,246,469, which simply detects thepassage of particles through a measuring region without any type ofqualitative analysis on the particles to discern “good” seed from otherdebris. The type of electronic circuitry required to enable the mixer(48) to be “programmed” to only produce an output signal upon detectionof a signal variation within an acceptable range is known to thoseskilled in the art.

3. Flow Rate or Velocity Monitoring of Individual Particles

In addition to counting individual particles, it may also be desirableto determine the velocity or flow rates of those passing analytes (14).If it is desired to detect velocity or flow rates of the analyte (14),it should be appreciated that two material sensors (10) 1 5 must beinterposed along the length of conduit (19) as shown in FIG. 4. Byinterposing two sensors (10) a known distance apart along the path oftravel of the analyte (14) two response signals will be obtained. Bydetecting the time difference between the two response signals, andsince the distance between the sensors (10) is known, the velocityand/or flow rate of the analyte (14) is easily calculated. Again, apractical use of such an application can be found in the example of theseed planter (60).

FIG. 4 illustrates the application of the present invention in which twosensors (10) are interposed along the length of conduit (19). The firstsensor and its constituent components are identified by the addition ofthe letter “a” after each respective numerical identifier and the secondsensor and its constituent components are identified by the addition ofthe letter “b” after each respective numerical identifier. It should beunderstood that when two sensors (10 a, 10 b)) are used, the electricalcircuit (40) for the material sensors (10 a, 10 b) of the presentinvention may be the same as that shown in FIG. 2, except that thesource (20) generates electromagnetic energy (30) for propagation intoboth the measuring regions (32 a, 32 b) and that the detector (22)detects the electromagnetic energy signal variations from both measuringregions (32 a, 32 b). Alternatively, each sensor (10 a, 10 b) may haveits own electrical circuit (40) as shown in FIG. 2.

Referring concurrently to FIG. 4 and FIG. 5, the response from the firstdetector (22 a) as the analyte (14) passes through the first measuringregion (32 a) may look like line “A” of FIG. 5 and the response from thesecond detector (22 b) as the analyte (14) passes through the secondmeasuring region (32 b) may look like line “B” of FIG. 5.

When the responses are differentiated with respect to time, responseslike those represented by lines “A′” and “B′” of FIG. 6 would result.The central portion “C” (FIG. 6) of the response lines A′ and B′ wouldbe flat for a longer time difference between the passing analyte (14).The differentiated response would then stay at zero for a period of timeas well. A zero crossing detector is then used to measure the timedifference “t” between the two measuring region responses. Because thedistance between the measuring regions (32 a, 32 b) is known, and thetime difference “t” is now known, the flow rate and/or velocity of theanalyte (14) can be readily determined. The electronic circuitryrequired to perform these tasks and the calculations required to makethese determinations is well known to those skilled in the art.

4. Flow Rate or Velocity Monitoring of Particles Flowing as a Continuum

The above example is appropriate for determining flow rates of discreetor individual particles separated by a measurable time period. However,for determining flow rates of a material or substance flowing as acontinuum, autocorrelation of the two response signals from the twomaterial sensors (10 a, 10 b) is preferred. A yield monitor for acombine harvester would be a specific application where monitorparticles flowing as a continuum would be useful.

Such an application is shown in FIG. 7. The sensors (10 a, 10 b) areinterposed along a length of conduit (19) where the analyte (14) isflowing as a continuum through a conduit (19). In an application of thepresent invention as a yield monitor for a combine harvester, theconduit (19) may be in any location where the grain flows through aconduit, for example in the area between the paddle elevators and thegrain tank fill auger.

For flow rate determinations of a material or substance (14) flowing asa continuum, the response from the first detector (22 a) may look likethe noisy signal as indicated by line “D” in FIG. 8, whereas theresponse from the second detector (22 b) may look like the noisy signalindicated by line “E” of FIG. 8. Using a sampling technique and acorrelation technique, a signal, similar to that indicated by Line “F”of FIG. 9, would result. The peak “G” (FIG. 9) of this signal wouldindicate the time delay between the two measuring regions (32 a, 32 b)and thus the flow rate. For high flow rates in which a greater volume ofmaterial passes per unit of time, the time difference would be less,whereas for lower flow rates, in which a lesser volume of materialpasses per unit of time, the time difference would be greater. In verylow flow rates or no flow rate, there would be no discernable signalpeak.

With the flow rate known, the volume of grain passing per unit of timemay be readily calculated. For example, if the conduit (19) flows fullat all times, the volume of the grain passing per unit of time iscalculated simply by multi plying the interior volume of the conduit bythe flow rate. If the conduit (19) is not flowing full at all times, oneof the material sensors (10 a, 10 b) may be used to also monitor thedielectric mass of the grain passing through the measuring region (32 a,32 b). With the dielectric mass known, the actual volume of grainpassing through the measuring region (32 a, 32 b) is readily quantified.The actual volume is then simply multiplied by the known flow rate toobtain the volume passing per unit of time. Once the volume of grain perunit of time is obtained, the yield per acre is readily obtained byknowing the speed of the harvester and the width of the harvester. Thiscalculated yield can then be displayed to the user on the console and/orstored in memory for later use and retrieval, such as to calculate theaverage yield per acre for a given field. The electronic circuitryrequired to perform these tasks and the calculations required to makethese determinations is well known to those skilled in the art.

5. Flow Rate Monitoring of Non-Turbulent Fluids

The technique just described for determining flow rates of materialsflowing as a continuum might also be used to measure flow rates ofnon-turbulent flow of fluid or gaseous materials. The determination offlow rates of non-turbulent fluid flow is useful, for example, in theagricultural industry for determining flow rates of aqueous mixturessuch as fertilizers, herbicides or insecticides applied bysprayer/applicators. Another example would be for monitoring the flowrates of gaseous materials under pressure such as in liquid anhydrousammonia applicators. Yet another example would be for monitoring gaseoussubstances flowing through pipes, conduits or hoses.

It should be understood, however, that a volume flow rate cannot bedetermined directly for a fluid or gaseous substances as in theabove-described technique for determining volume flow rates of solidgranular materials flowing as a continuum. Instead, the velocity of thefluid or gaseous substance is determined by detecting inclusions(macroscopic and/or microscopic gaseous bubbles or “dirt” particles) inthe fluid or gas. Detecting these inclusions and their correlation attwo different points along a flow line will result in the determinationof flow velocity of the liquid or gas.

Consider a set of particles tightly grouped at one point in a fluidflow. If the distribution of the particles is assumed to be Gaussian atsome average value, their values might be described as:${D(x)} = {D_{0}^{{- \frac{1}{2}}\quad \frac{{({x - x_{0}})}^{2}}{\sigma^{2}}}}$

At a later period in time, these same number of particles will be foundat some other location. The distribution at this later or second periodin time might be described as:${D(x)} = {D_{0}^{\prime}^{{- \frac{1}{2}}\quad \frac{{({x - x_{0}^{\prime}})}^{2}}{\sigma^{\prime 2}}}}$

The primed values stand for constants in the distribution at the secondperiod in time. It would be expected that the distribution would have“spread” and that σ′ would relate to a distribution which is spread out.When the standard deviation σ is small, the distribution is “sharp”.When σ is large, the distribution is spread out. Sampling thisdistribution of particles as they flow past the two measuring regions(32 a, 32 b) will produce a digital representation of the number ofparticles versus time. Depending on the flow rate, the number ofparticles in the distribution may be counted more than once. However,the shape of the distribution is important. If the sampling rate is toosmall, only the total number of particles would be counted if theyhappen to be in the measurement region at that time. As the samplingrate increases, a point will be reached when the distribution will beadequately measured and the average of the distribution can be detected.The average at some time later, even though the distribution has spreadwould also be detected and a flow rate determined from that. When thedistribution is “continuous”, then one looks for fine structure in thedistribution and cross correlates to measurements to determine the timeof flow between the two measuring regions (32 a, 32 b).

Once the flow velocity is obtained one can then determine volume flow,such as in gallons or liters per unit of time, by simply multiplying thecross-sectional area of the flowing fluid or gas by the flow velocity ofthe fluid. If the measuring region (32) is flowing full at all times,such as with a liquid under pressure or a gaseous substance, the area ofthe measuring region is equal to the cross-sectional area of the flowingfluid or gas. If the measuring region (32) is not flowing full, thedielectric volume of the flowing substance may be determined asexplained below, this dielectric volume may be used to calculate theactual volume of material passing per unit of time.

In practice, first and second material sensors (10 a, 10 b) must beinterposed in the conduit (19) along the path of travel of the fluid orgaseous analyte substance (14) as shown in FIG. 10. As the analyte (14)passes the material sensors (10 a, 10 b), each will produce a responsesignal proportional to the dielectric volume, the magnetic volume, orthe conducting volume of the analyte (14). By measuring both themagnitude of the response of each sensor (10 a, 10 b) and the time delaybetween the responses of the two sensors (10 a, 10 b) the velocity ofthe inclusions (80) in the fluid or gaseous substance (14), and thus thevelocity of the fluid or gas (14) itself can be determined and thenconverted to volume flow rate as described above. The electroniccircuitry required to perform these tasks and the calculations requiredto make these determinations is well known to those skilled in the art.

Additionally, those skilled in the art will recognize that modificationsof these circuits can be made to incorporate modulation of amplitudeand/or phase on the carrier of the signals so that time delays used onthe signals effect the same result as a delay in the detected signals.The effective modulation time delays can be varied to give a correlationpeak without having to delay the sensed signal phase delay.

6. Flow Rate Determinations of Substances Flowing as a Continuum Usingthe Doppler Technique.

Another embodiment for determining flow rates of solid, liquid, orgaseous substances flowing as a continuum is shown in FIG. 11. Notice,with the Doppler technique, only one sensor (10) is required as opposedto two sensors for the other above-described techniques for determiningflow rates. Additionally, a single diode (90) extends through a singleport (92) in the wall members (13) of the chamber (16), the single diode(90) acting as both the electromagnetic energy source (24) andelectromagnetic energy detector (26). With the Doppler technique, thesignal that leaves the area of the sensor returns from the flowingmaterial shifted in frequency. The mixer (48) receiving thisfrequency-shifted return signal will now produce an output signal at afrequency that is equal to this shift of frequency between thetransmitted signal and the received signal. The low frequency signalwill be related to the velocity of the material being detected and thusrelated to the flow rate.

The transmitted signal will have a substantial reflection coefficient.Then this return signal is electrically mixed with the incident signal.The resulting signal difference frequency is filtered out of thedetector and is indicative of the velocity of the material. Theelectronic circuitry required to perform these tasks and thecalculations required to make these determinations is well known tothose skilled in the art.

Although only exemplary embodiments of the present invention and variousapplications therefor have been described in detail above, those skilledin the art will readily appreciate that many modifications are possiblewithout materially departing from the novel teachings and advantages ofthis invention and its various applications.

Accordingly, all such modifications are intended to be included withinthe scope of this invention as defined in the following claims.

We claim:
 1. A non-resonant electromagnetic energy sensor comprising:(a) housing having wall members surrounding a path of travel of ananalyte, said wall members defining a chamber having an interior volumefor passage of said analyte therethrough, at least a portion of saidchamber including at least one measuring region; (b) a non-resonantelectromagnetic energy circuit, said circuit comprising: (i) a powersource; (ii) at least one electromagnetic energy source in communicationwith said interior volume of at least one of said measuring regions,said a least one electromagnetic energy source generatingelectromagnetic energy having electrical and magnetic components ofnon-equal total peak values; (iii) at least one electromagnetic energydetector in communication with said interior volume of at least one ofsaid measuring regions, said at least one electromagnetic energydetector producing an output signal upon detection of signal variationsin said electromagnetic energy within at least one of said measuringregions caused by passage of said analyte therethrough.
 2. Thenon-resonant electromagnetic energy sensor of claim 1 wherein saidmeasuring region is defined by a dielectric region disposed betweenevanescent regions.
 3. The non-resonant electromagnetic energy sensor ofclaim 1 wherein said at least one electromagnetic energy source and saidat least one electromagnetic energy detector is at least one singlediode acting as both said at least one electromagnetic energy source andsaid at least one electromagnetic energy detector.
 4. The non-resonantelectromagnetic energy sensor of claim 1 wherein said non-resonantelectromagnetic energy circuit further includes a buffer amplifier. 5.The non-resonant electromagnetic energy sensor of claim 4 wherein saidnon-resonant electromagnetic energy circuit further includes a signalprocessor.
 6. The non-resonant electromagnetic energy sensor of claim 5wherein said generated electromagnetic energy has a frequency of atleast 10 megahertz.
 7. A planter monitoring system for use with aconventional row crop planter, said planter of the type having at leastone conduit defining a path of travel through to the soil for dispensingsolid granular analyte particles thereon, said monitoring systemcomprising: (a) a non-resonant electromagnetic energy sensor interposedin said at least one conduit along the path of travel of said analytestherethrough, said non-resonant electromagnetic energy sensorcomprising: (i) a housing having wall members surrounding said path oftravel of said analyte, said wall members defining a chamber having aninterior volume for passage of said analyte therethrough, at least aportion of said chamber including at least one measuring region definedby a dielectric region disposed between evanscent regions; (ii) anon-resonant electromagnetic energy circuit, said circuit comprising:(A) a power source; (B) at least one electromagnetic energy source incommunication with said interior volume of at least one of saidmeasuring region, said electromagnetic energy source generatingelectromagnetic energy having electrical and magnetic components ofnon-equal total peak values; (C) at least one electromagnetic energydetector in communication with said interior volume of said at least onemeasuring region, said electromagnetic energy detector producing anoutput signal upon detection of signal variations in saidelectromagnetic energy within at least one of said measuring regioncaused by passage of said analyte therethrough; (b) a monitorinterfacing with said non-resonant electromagnetic energy sensor, saidmonitor being electronically responsive to said output signals from saidat least one electromagnetic energy detector.
 8. The planter monitoringsystem of claim 7 wherein said monitor includes indicators for visuallyindicating said analyte flow through said at least one measuring region.9. The planter monitoring system of claim 7 wherein said monitorincludes indicators for audibly indicating said analyte flow throughsaid at least one measuring region.
 10. The planter monitoring system ofclaim 7 wherein said monitor includes a counter to count the passage ofsaid analytes passing through said at least one measuring region. 11.The planter monitoring system of claim 7 wherein said system includeselectronic circuitry programed to control said electromagnetic energydetector to output signals only when said detected signal variationsfall within a predetermined range of acceptable signal variations.
 12. Aflow rate monitoring system for monitoring flow rates of discrete solidgranular analyte particles through a conduit, said flow rate monitoringsystem comprising: (a) a non-resonant electromagnetic energy sensorinterposed in said conduit along the path of travel of said analytestherethrough, said non-resonant electromagnetic energy sensorcomprising: (i) a housing having wall members surrounding said path oftravel of said analytes, said wall members defining a chamber having aninterior volume for passage of said analyte therethrough, at least aportion of said chamber including a first measuring region and a secondmeasuring region at a predetermined spaced distance, said first andsecond measuring regions defined by a dielectric region disposed betweenevanscent regions; (ii) a non-resonant electromagnetic energy circuit,said circuit comprising: (A) a power source; (B) at least oneelectromagnetic energy source in communication with said interior volumeof said first and second measuring regions, said at least oneelectromagnetic energy source generating electromagnetic energy withinsaid first and second measuring regions having electrical and magneticcomponents of non-equal total peak values; (C) at least oneelectromagnetic energy detector in communication with said interiorvolume of said first and second measuring regions, said at least oneelectromagnetic energy detector producing an output signal upondetection of signal variations of said electromagnetic energy withinsaid first and second measuring regions caused by passage of saidanalyte therethrough; (b) a monitor interfacing with said non-resonantelectromagnetic energy sensor, said monitor being electronicallyresponsive to said output signals from said at least one electromagneticenergy detector.
 13. The flow rate monitoring system of claim 12 whereinsaid system further includes electronic circuitry programmed to receivesaid output signals from said at least one electromagnetic energydetector, said programmed electronic circuitry further includingcircuitry for detecting a time delay between said output signals wherebysaid analyte flow rate is determined by dividing said predeterminedspaced distance of said first and second measuring regions by saiddetected time delay.
 14. A flow rate monitoring system for monitoringflow rates of solid granular analyte particles flowing as a continuumthrough a conduit, said flow rate monitoring system comprising: (a) anon-resonant electromagnetic energy sensor interposed in said conduitalong the path of travel of said analytes therethrough, saidnon-resonant electromagnetic energy sensor comprising: (i) a housinghaving wall members surrounding said path of travel of said analytes,said wall members defining a chamber having an interior volume forpassage of said analyte therethrough, at least a portion of said chamberincluding a first measuring region and a second measuring region at apredetermined spaced distance, said first and second measuring regionsdefined by a dielectric region disposed between evanscent regions; (ii)a non-resonant electromagnetic energy circuit, said circuit comprising:(A) a power source; (B) at least one electromagnetic energy source incommunication with said interior volume of said first and secondmeasuring regions, said at least one electromagnetic energy sourcegenerating electromagnetic energy within each of said first and secondmeasuring regions having electrical and magnetic components of non-equaltotal peak values; (C) at least one electromagnetic energy detector incommunication with said interior volume of said first and secondmeasuring regions, said at least one electromagnetic energy detectorproducing an output signal upon detection of signal variations of saidelectromagnetic energy within each of said first and second measuringregions caused by passage of said analyte therethrough; (b) a monitorinterfacing with said non-resonant electromagnetic energy sensor, saidmonitor being electronically responsive to said output signals from saidat least one electromagnetic energy detector.
 15. The flow ratemonitoring system of claim 14 wherein said system further includeselectronic circuitry programmed to receive said output signals from saidat least one electromagnetic energy detector, said programmed electroniccircuitry further including circuitry for detecting a time delay betweensaid output signals whereby said analyte continuum flow rate isdetermined by dividing said predetermined spaced distance of said firstand second measuring regions by said detected time delay.
 16. The flowrate monitoring system of claim 15 wherein said system is a yieldmonitor for a harvester, wherein said yield monitor further includecircuitry to calculate yield based on said analyte continuum flow rate.17. A volume flow rate monitoring system for monitoring volume flowrates of non-turbulent fluids through a conduit, said fluid havinginclusions therein, said flow rate monitoring system comprising: (a) anon-resonant electromagnetic energy sensor interposed in said conduitalong the path of travel of said fluid therethrough, said non-resonantelectromagnetic energy sensor comprising: (i) a housing having wallmembers surrounding said path of travel of said fluid, said wall membersdefining a chamber having an interior volume for passage of said fluidtherethrough, at least a portion of said chamber including a firstmeasuring region and a second measuring region at a predetermined spaceddistance, said first and second measuring regions defined by adielectric region disposed between evanscent regions; (ii) anon-resonant electromagnetic energy circuit, said circuit comprising:(A) a power source; (B) at least one electromagnetic energy source incommunication with said interior volume of said first and secondmeasuring regions, said at least one electromagnetic energy sourcegenerating electromagnetic energy within said first and second measuringregions having electrical and magnetic components of non-equal totalpeak values; (C) at least one electromagnetic energy detector incommunication with said interior volume of said first and secondmeasuring regions, said at least one electromagnetic energy detectorproducing an output signal upon detection of signal variations of saidelectromagnetic energy within each of said first and second measuringregions caused by passage of said inclusions in said fluid therethrough;(b) a monitor interfacing with said non-resonant electromagnetic energysensor, said monitor being electronically responsive to said outputsignals from said at least one electromagnetic energy detector.
 18. Thevolume flow rate monitoring system of claim 17 wherein said systemfurther includes electronic circuitry programmed to receive said outputsignals from said at least one electromagnetic energy detector, saidprogrammed electronic circuitry further including circuitry fordetecting a time delay between said output signals, whereby a velocityof said inclusions is determined by dividing said predetermined spaceddistance of said first and second measuring regions by said timedifference, said volume flow rate determined by multiplying saidinclusion velocity by a volume of said non-turbulent fluid in one ofsaid first and second measuring regions.
 19. The flow rate monitoringsystem of claim 18 wherein said system is used on a sprayer/applicator.20. The flow rate monitoring system of claim 18 wherein said system isused on an anhydrous ammonia applicator.
 21. A flow rate monitoringsystem for determining flow rates of solid, liquid or gaseous analyteflowing as a continuum using Doppler techniques, said monitoring systemcomprising: (a) a non-resonant electromagnetic energy sensor interposedin said conduits along the path of travel of said analytes therethrough,said non-resonant electromagnetic energy sensor comprising: (i) ahousing having wall members surrounding said path of travel of saidanalyte, said wall members defining a chamber having an interior volumefor passage of said analyte therethrough, at least a portion of saidchamber including at least one measuring region defined by a dielectricregion disposed between evanscent regions; (ii) a non-resonantelectromagnetic energy circuit, said circuit comprising: (A) a powersource; (B) at least one electromagnetic energy source in communicationwith said interior volume of said at least one measuring region, said atleast one electromagnetic energy source generating a transmit signal ofelectromagnetic energy at first frequency having electrical and magneticcomponents of non-equal total peak values; (C) at least oneelectromagnetic energy detector in communication with said interiorvolume of said at least one measuring region, said at least oneelectromagnetic energy detector receiving a return signal having asecond frequency resulting from a shift in frequency of said transmittedsignal returning from said flowing analyte, said electromagnetic energydetector producing an output signal at a third frequency equal to theshift of frequency between said transmitted signal and said returnsignal; (b) a monitor interfacing with said non-resonant electromagneticenergy sensor, said monitor being electronically responsive to saidoutput signals from said at least one electromagnetic energy detector.22. The flow rate monitoring system of claim 21 wherein said systemfurther includes electronic circuitry programmed to receive said outputsignals from said at least one electromagnetic energy detector andcircuitry for converting said output signal having said third frequencyto a velocity of said substance and circuitry for converting saidvelocity to a flow rate.